Environmental Protection Agency Administrator Gina McCarthy offered a blunt defense Monday of the Obama administration’s new rule to cut carbon dioxide pollution, touting its benefits against mounting criticism from the coal industry and some members of Congress.

“Given the astronomical price we pay for climate inaction, the most costly thing we can do is to do nothing,” McCarthy told a room full of staff members and environmental allies at the EPA headquarters in Washington.

She added: “There are still special interest skeptics who will cry the sky is falling. Who will deliberately ignore the risks, overestimate the costs, and undervalue the benefits. But the facts are clear. For over four decades, EPA has cut air pollution by 70% and the economy has more than tripled.”

Arguably the most important step any country has taken to combat climate change, the new rule focuses on fossil fuel-burning power plants. They account for 40% of U.S. emissions, making them the single biggest source of carbon dioxide emissions, the main driver of global warming.

The proposed rule seeks to reduce power plant emissions by 30% from 2005 levels by 2030. Carbon dioxide emissions have already fallen more than 10% since 2005, which would make the effective reduction more like 15% to 17%, experts said.

The EPA has proposed individual state targets based on each state’s fuel mix, with coal states starting and ending at a higher emissions level than those that use more of cleaner-burning natural gas and renewables. The states can then pick from a menu of options in order to achieve the cuts.

The Obama administration has long held that combating climate change is about protecting public health and economic growth, and to underscore that, the president will make his own comments later in the day in a press call with the American Lung Assn.

In her comments, McCarthy stuck to the same themes. She opened her speech with an anecdote about seeing Parker Frey, an active but severely asthmatic 10-year-old boy, on a recent trip she took to a Cleveland clinic. McCarthy said Parker’s mother told her that on some days, the air quality is so poor that it was dangerous for the boy to play outdoors.

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“In the United States of America, no parent should ever have that worry,” she said. “That’s why EPA exists. Our job, directed by our laws, reaffirmed by our courts, is to protect public health and the environment. Climate change, fueled by carbon pollution, supercharges risks not just to our health, but to our communities, our economy and our way of life.”

McCarthy said critics who warn of severe economic consequences of the rules have historically decried all environmental protections. She described them as “ special interests” who “cried wolf to protect their own agenda. And time after time, we followed the science, protected the American people, and the doomsday predictions never came true. Now, climate change is calling our number. And right on cue, those same critics once again will flaunt manufactured facts and scare tactics.”

Before the rules came out, the U.S. Chamber of Commerce said it would cost the economy $50 billion annually and hundreds of thousands of jobs. Senate minority leader Mitch McConnell, from the coal-heavy state of Kentucky, called it “a dagger in the heart of the American middle class.”